Contact-free pushbutton switching device

ABSTRACT

A permanent magnet having a pole shoe is affixed to a moving device for moving the magnet in directions transverse to the axis of magnetization of the magnet and into and out of close proximity with a galvanomagnetic resistance affixed to an iron yoke.

United States Patent Samberger et a].

[ 51 Jan. 18, 1972 [54] CONTACT-FREE PUSHBU'ITON SWITCHING DEVICE Inventors: Konrad Samberger, Gailon; Ulrich l-lruschka; Karl Greger, both of Amberg, all of Germany Siemens Aktiengesellschal't, Berlin and Munich, Germany Filed: Mar. 27, 1970 Appi. No.: 23,375

Assignee:

[30] Foreign Application Priority Data Mar. 29, 1969 Germany ..P 19 16 336.1

US. Cl.

Int. Cl.

Field ofSearch ..338/32 S; 323/94 H; 335/205; 307/116 [56] References Cited UNITED STATES PATENTS 3,286,161 11/1966 Jones et al. ..323/94 H 3,448,419 6/1969 Myatt ..335/207 Primary Examiner-Herman J. l-lohauser Attorney-Curt M. Avery, Arthur E. Wilfond, Herbert L. Lerner and Daniel J. Tick [57] ABSTRACT A permanent magnet having a pole shoe is affixed to a moving device for moving the magnet in directions transverse to the axis of magnetization of the magnet and into and out of close proximity with a galvanomagnetic resistance affixed to an iron yoke.

8 Claims, 4 Prawlng Figures CONTACT-FREE PUSHBUTTON SWITCHING DEVICE DESCRIPTION OF THE INVENTION The invention relates to a switching device. More particularly, the invention relates to a contact-free pushbutton switching device. The switching device utilizes a permanent magnet which is movable relative to a stationary galvanomagnetic resistance or field plate affixed to an iron yoke.

In a known pushbutton switching device of the type of the invention, described in the German printed document GM 1,993,051, a permanent magnet is movable in its direction of magnetization relative to its longitudinal axis. The permanent magnet has a separate pole shoe positioned transversely to the longitudinal direction of said magnet. The pole shoe points to a galvanomagnetic resistance which is affixed to a part of the switch. The galvanomagnetic resistance is positioned in a magnetically conductive tube comprising a yoke portion for the magnetic flux issuing from the permanent magnet and conducted via the pole shoe and the galvanomagnetic resistance or field plate. In order to close the magnetic circuit, a magnetically conductive carrier is provided at the pole of the magnet opposite its pole shoe. The magnetically conductive carrier is in contact with the yoke portion via an air gap.

In the aforedescribed known arrangement, the pole shoe functions as a wedge in order to concentrate the magnetic field lines on the surface of the galvanomagnetic resistance. However, since the known arrangement provides the magnetic circuit with a plurality of junction or transition points from one medium to the other, to increase the magnetic reluctance, it is necessary to make the permanent magnet relatively large. The junction points include, for example, the transition points from the permanent magnet to the carrier and to the pole shoe and from the carrier to the tubular yoke. The occurring stray fluxes, which are not supplied to the galvanomagnetic resistance, are not taken into consideration at this point. A spring is provided for the pushbutton. The spring is wound around the permanent magnet and is magnetically conductive sothat it removes part of the energy from the magnet.

Gennan printed document GM 1,965,246 discloses an arrangement in which a galvanomagnetic resistance is positioned in the airgap of a premagnetizing circuit. The galvanomagnetic resistance is excited by a permanent magnet. The airgap is bridged by a soft magnetic body which is movable relative to the airgap, for the purpose of changing the resistance of the galvanomagnetic resistance. In this arrangement, there is relatively low effectiveness with respect to the utilization of the useful flux emanating from the permanent magnet.

The principal object of the invention is to provide a new and improved contact-free switching device.

An object of the invention is to provide a contact-free switching device of relatively small dimensions.

An object of the invention is to provide a contact-free switching device which provides good utilization of the useful flux issuing from the permanent magnet in order to provide switching operations.

An object of the invention is to provide a contact-free switching device of simple structure and efficiency, effectiveness and reliability in operation.

In accordance with the invention, the direction of movement of the permanent magnet is transverse to the longitudinal axis and the axis of magnetization of the permanent magnet. An extensive separation in the airgap continuity of the magnetic circuit of the switching device is permissible due to the arrangement of the magnet within a frame-shaped unitary yoke member. The magnet is movable relative to the yoke member and to at least one galvanomagnetic resistance which is affixed to the inside longitudinal side of the yoke. This permits the mounting of the active elements of the switching device outside the actual housing thereof, and is of practical importance in the adjustment of the switching device. Furthermore, it is preferred to support the magnet on a tappet of a pushbutton and to guide the tappet through the transverse side of the yoke frame. In order to permit the subordination of the terminals to the galvanomagnetic resistance by premounting their active parts and to simplify the premounting operations, the guide recesses for the insertion of the tappet are preferably maintained open toward the flat side of the yoke frame and a synthetic plate is positioned on the flat side. The-circuitry, including amplifier elements, is mounted on the synthetic plate, and the synthetic plate guides the tappet in its movement.

The permanent magnet is affixed to the tappet in a simple fashion by pressing such magnet into an opening formed in the tappet. The magnet remains self-affixed in the opening in the tappet. In order to enlarge the premounted unit still further, so that all necessary components which function electrically may be combined in the unit and the unit need only be inserted into the housing of the switching device, the synthetic plate is provided with electrically connected plugs which are mounted in a cover portion of the housing. The spring is completely separate from the magnetic circuit and abuts against the yoke and against a metal bracket mounted on the end of the tappet. The pushbutton has a pushbutton head which is separate from the tappet and has an inside which abuts against the metal frame under spring pressure and is held by inserts which project behind protrusions formed in the housing of the switch.

In accordance with the invention, a contact-free switching device comprises an iron yoke. A galvanomagnetic resistance is affixed to the yoke. A permanent magnet has a pole shoe and a longitudinal axis of magnetization. Moving means affixed to the magnet moves the magnet in directions transverse to its axis of magnetization and into and out of close proximity with the galvanomagnetic resistance.

The yoke is a frame-type unitary member having an inside longitudinal side. At least one galvanomagnetic resistance is positioned at the inside longitudinal side of the yoke. The moving means moves the magnet within the yoke.

The moving means comprises a pushbutton and a tappet in abutment with the pushbutton. The tappet comprises insulating material and supports the magnet and extends into the yoke.

The yoke has a flat side and a guide recess formed therein and open toward the flat side to accommodate the tappet of the moving means. A plate of synthetic material is provided at the flat side of the yoke and guidesthe tappet in its movement. An amplifier circuit is mounted on the plate. The tappet of the moving means has opening formed therein and the magnet is held in the opening.

A housing encloses the switching device. The housing has a cover portion. Electrically connective plugs are supported by the cover portion and extend from the amplifier circuit mounted on the plate.

A bracket is mounted on the end of the tappet of the moving means which abuts the pushbutton and abuts the pushbutton. A spring on the tappet abuts at one end against the bracket and abuts at its other end against the yoke.

The pushbutton is separate from the tappet and has an inside surface abutting the bracket under the pressure of the spring. The housing enclosing the switching device has protrusions formed therein. Inserts support the pushbutton in the housing and extend behind the protrusions.

In another embodiment of the switching device of the invention, the spring abuts at one end directly against the pushbutton and abuts at the other end against the yoke.

In order that the invention may be readily carried into effect, it will now be described with reference to the accompanying drawing, wherein:

FIG. 1 is a schematic diagram, partly in section, of an embodiment of the contact-free switching device of the invention;

FIG. 2 is a schematic diagram, partly in section, of the embodiment of FIG. 1, taken in a plane perpendicular to that of the plane of illustration of FIG. I;

FIG. 3 is a schematic diagram, partly in section, of another embodiment of the switching device of the invention; and

FIG. 4 is a schematic diagram, partly in section, of the embodiment of FIG. 3 in assembled condition.

In the FIGS., the same components are identified by the same reference numerals.

As shown in FIGS. 1 and 2, the contact-free pushbutton switching device of the invention comprises a stationary tubular housing 1 of electrically insulating material. One end of the tube 1 has a cover portion 2. The cover portion 2 has inserts 4a and 4b which may be snapped into corresponding recesses 3a and 3b formed in the housing 1. The switching is operated by a pushbutton head 5. The pushbutton head 5 has inserts or arms which may be snapped into position behind protrusions formed in the housing 1.

The pushbutton head 5 may also be snapped into the housing 1 via inserts or arms 6 and 7. The arms 6 function as guides during the movement or operation of the pushbutton 5. The movement of the pushbutton S is transmitted by a tappet 9. A permanent magnet 10 is affixed to the tappet 9 and is moved, with said tappet, relative to an iron yoke 11.

In the illustrated embodiment, two galvanomagnetic resistances or field plates 12 and 13 are affixed to the iron yoke 11. The longitudinal axis and the axis of magnetization of the permanent magnet 10 coincide and said magnet is so positioned on the tappet 9 that said axis of magnetization moves transversely to the direction of movement of said tappet. The iron yoke is a frame-type unitary member having an inside Iongitudinal side 14. The galvanomagnetic resistances l2 and 13 are afiixed to the inside longitudinal side 14 of the yoke 11.

In order to further concentrate the field lines on the galvanomagnetic resistances l2 and 13, the permanent magnet 10 is provided with a pole shoe type attachment 15. Two guide recesses 16 and 17 are provided in the yoke 11 to guide the tappet 9 along the transverse sides 18 and 19 of said yoke. An opening or recess 19 is formed in the tappet 9 and the permanent magnet 10 is pressed into said opening, so that it remains affixed therein in a self-holding manner. This may be accomplished with the assistance of protruding inserts which withdraw while the magnet is inserted.

The galvanomagnetic resistances l2 and 13 are acted upon alternately by the magnetic flux of the permanent magnet 10, so that said resistances are alternately either high ohmic or of high resistance, or low ohmic or of low resistance. The high ohmic or high electrical resistance may be compared with an open contact and the low ohmic or low electrical resistance may be compared with a closed contact. The galvanomagnetic resistances 12 and 13 have a high electrical resistance when they are influenced by the magnetic field of the permanent magnet 10.

In order to place the tappet 9 in the yoke 11 in a simple manner, the guide recesses 16 and 17 open toward a flat side 20 of said yoke. The guide recesses 17 are covered by a plate 21 of synthetic electrically insulating material 21. The plate 21 is mounted on the flat side 20 of the yoke 11. The plate 21 supports amplifier components 22a, 22b and 23a, 23b. The amplifier components 22a, 22b and 23a, 23b are interconnected by a printed circuit on the plate 21. The terminals of the printed circuit on the plate 21 are connected to the outside via electrically connective plugs 24 and 25. The plug connections 24 and 25 are mounted in, and supported by, the cover 2 of the housing 1. Thus, the cover 2, the synthetic plate 21 and the plugs 24 and 25 together form a unit.

The tappet 9 has guide attachments 26 and 27 which bear against the plate 21 when said plate and the yoke 11 are in assembled condition. The guide attachments 26 and 27 simultaneously function to better support the magnet 10 in the tappet 9. The unit composed of the yoke 11, the tappet 9, the plate 21 and the cover 2 also comprises, in the embodiment of FIGS. 1 and 2, a metal bracket 28. The metal bracket 28 is installed on the pushbutton head 5 prior to mounting in the housing 1.

A compression spring 29 is mounted around the tappet 9. One end of the spring 29 abuts against the bracket 28 and the other end of said spring abuts against the yoke member 11. The free end of the bracket 28 engages a recess 30 formed in the pushbutton head 5, as soon as said pushbutton head has been assembled with the remainder of the switch.

The complete assembled switching device is inserted into the tubular housing 1, from the right-side opening of said tubular housing, until the inserts or arms engage or snap into the recesses or openings 3a and 3b. The recesses 3a and 3b function to open the switch, since after said switch is assembled, the inserts at the pushbutton 5 are no longer accessible from outside the housing 1. The pushbutton head 5 is preferably locked in the housing portion 1 prior to the insertion of the unit with the inserts 6 and 7.

The metal bracket 28 is eliminated in the embodiment of FIGS. 3 and 4. The tappet 9 has an annular slot 31 formed therein. As shown in FIG. 4, the annular slot 31 of the tappet 9' is engaged by spring biased or resilient elements 320 and 32b of the pushbutton head 5. The return movement of the tappet 9 is thus directly effected by the pushbutton head 5', since said head moves said tappet along with it via the attachments 32a and 32b.

In addition to the elimination of the metal bracket 28, the embodiment of FIGS. 3 and 4 also provides a simplified mounting arrangement relative to that of the embodiment of FIGS. 1 and 2. The plate 21' is first inserted into the housing from the right-hand end (FIGS. 1 and 2) until the inserts 4a and 4b snap into their corresponding recesses 3a, 3b (FIG. 1). The spring 29 is then inserted from the pushbutton or lefthand end (FIGS. 1 and 2) and the pushbutton head 5' is then snapped on. The pushbutton head 5 is snapped into the housing via its inserts 7 (FIGS. 1 and 2) and via the attachments 32a and 32b in their engagement with the annular slot 31 of the tappet 9.

In the embodiment of FIGS. 3 and 4, the transversely mounted permanent magnet 10' may also be provided without its pole shoe 15. Adequate bunching may be provided for the pushbutton, in accordance with the invention, without the pole shoe of the magnet. The function of the pushbutton, in accordance with our invention, is clearly illustrated by the drawing and need not be further explained.

The entire useful flux of the permanent magnet 10' is transferred into the yoke 11' via the pole shoe [5 and the galvanomagnetic resistance 12. Since the yoke 11 no longer includes an airgap, the magnetic flux is divided between both transverse sides and will enter the pole of the magnet 10, which pole is positioned opposite the galvanomagnetic resistance 12'.

In comparison with the known arrangements, only two increases in magnetic reluctance may be considered in the present invention. If the pushbutton head 5', and thus the tappet 9 and the magnet 10', are moved relative to the yoke 11' and the galvanomagnetic resistance 12', the lines of force produced by said magnet enter directly into said yoke for a period of time until the pole shoe attachment 15' is in close proximity with the galvanomagnetic resistance 13. The galvanomagnetic resistances l2 and 13 thus function as opening and closing contacts.

It is thus seen that the switching device of our invention is a simple, contactfree design having smaller space requirements than known arrangements and having considerably reduced mounting or assembling costs relative to known arrangements.

In the manufacture of the switching device of the invention, it is particularly advantageous to produce the frame type yoke 11 of sintered material. This permits dispensing with a metalremovmg process.

While the invention has been described by means of specific examples and in specific embodiments, we do not wish to be limited thereto, for obvious modifications will occur to those skilled in the art without departing from the spirit and scope of the invention.

We claim:

1 A contact-free switching device, comprising an iron yoke comprising a frame type unitary member having an inside longitudinal side;

at least one galvanomagnetic resistance affixed to said yoke and positioned at the inside longitudinal side of said yoke; a permanent magnet having a pole shoe and a longitudinal axis of magnetization; and

moving means affixed to said magnet for moving said magnet within said yoke in directions transverse to its axis of magnetization and into and out of close proximity with said galvanomagnetic resistance.

2. A contact-free switching device as claimed in claim 1, wherein said moving means comprises a pushbutton and a tappet in abutment with said pushbutton, said tappet comprising insulating material and supporting said magnet and extending into said yoke.

3. A contact-free switching device as claimed in claim 2, wherein said yoke has a flat side and a guide recess formed therein and open toward said flat side to accommodate the tappet of said moving means, and further comprising a plate of synthetic material provided at the flat side of said yoke and guiding said tappet in its movement, and amplifier means mounted on said plate.

4. A contact-free switching device as claimed in claim 2, wherein the tappet of said moving means has an opening formed therein and said magnet is held in said opening.

5. A contact-free switching device as claimed-in claim 3, further comprising a housing enclosing said switching device,

said housing having a cover portion, electrically connective plugs supported by said cover portion and extending from the amplifier means mounted on said plate.

6. A contact-free switching device as claimed in claim 3, further comprising a bracket mounted on the end of the tappet of said moving means abutting said pushbutton and abutting said pushbutton and a spring on said tappet and abutting at one end against said bracket and abutting at its other end against said yoke.

7. A contact-free switching device as claimed in claim 6. wherein the pushbutton is separate from the tappet of said moving means and has an inside surface abutting said bracket under the pressure of said spring, and further comprising a housing enclosing said switching device, said housing having protrusions formed therein, and inserts supporting said pushbutton in said housing and extending behind said protrusions.

8. A contact-free switching device as claimed in claim 6. wherein said spring abuts at said one end directly against said pushbutton and abuts at said other end against said yoke.

I I i i i 

2. A contact-free switching device as claimed in claim 1, wherein said moving means comprises a pushbutton and a tappet in abutment with said pushbutton, said tappet comprising insulating material and supporting said magnet and extending into said yoke.
 3. A contact-free switching device as claimed in claim 2, wherein said yoke has a flat side and a guide recess formed therein and open toward said flat side to accommodate the tappet of said moving means, and further comprising a plate of synthetic material provided at the flat side of said yoke and guiding said tappet in its movement, and amplifier means mounted on said plate.
 4. A contact-free switching device as claimed in claim 2, wherein the tappet of said moving means has an opening formed therein and said magnet is held in said opening.
 5. A contact-free switching device as claimed in claim 3, further comprising a housing enclosing said switching device, said housing having a cover portion, electrically connective plugs supported by said cover portion and extending from the amplifier means mounted on said plate.
 6. A contact-free switching device as claimed in claim 3, further comprising a bracket mounted on the end of the tappet of said moving means abutting said pushbutton and abutting said pushbutton and a spring on said tappet and abutting at one end against said bracket and abutting at its other end against said yoke.
 7. A contact-free switching device as claimed in claim 6, wherein the pushbutton is separate from the tappet of said moving means and has an inside surface abutting said bracket under the pressure of said spring, and further comprising a housing enclosing said switching device, said housing having protrusions formed therein, and inserts supporting said pushbutton in said housing and extending behind said protrusions.
 8. A contact-free switching device as claimed in claim 6, wherein said spring abuts at said one end directly against said pusHbutton and abuts at said other end against said yoke. 